I'm posting this under the Dyna's becase I ride a FatBob. The answers to this post will probably be different depending on your engine and mod's done. I ride 15 miles one way to work with 8 miles of the ride at 35 miles an hour speed limit. I'm usually with traffic in 3rd gear doing 35 but when traffic is moving we are doing 40 and I shift to 4th. Back and forth, back and forth. Would you just keep it in 3rd and cruse to 40 to 45? I do not have a tach. But telling what gear your in is easily done with speed. I don't want to lug the engine but at 40 to 45, it seems I'm exceeding the rpm's for 3rd gear. My bike rides great in 4th gear doing 45. But at 40mph it seems I'm lugging the engine. I hate 3rd gear. In 3rd gear, what's your crusing speed? When will you shift to 4th gear knowing your going to be kicking it back down to 3rd?